Combustion Characteristic Study Of A Single DC Combustor

The single-head DC combustion chamber is an important step in the design of aeroengines to test the characteristics of the combustion organization.This article aims to study the combustion characteristics of a single-head DC combustor through a combination of experiment and numerical simulation.Completed the design of the single-head DC model combustion chamber,determined the size limit of the combustion chamber by combing the working conditions of the combustion chamber,carried out the design of the flame tube,comprehensively considered the gas distribution of each part of the combustion chamber,and completed the mixing hole and cooling of the combustion chamber.A standard single-head DC model combustion chamber was formed and an aviation kerosene/air single-head combustion chamber experimental system was built.Using STAR-CCM+software to select the appropriate turbulence model,combustion model,radiation model,pollutant emission model and reasonable boundary condition settings.The simulation of the reaction of multiphase fluid in single-head DC combustion chamber was carried.The effects of different fuel-air ratios,different inlet air temperatures,and different intake air flow rates on the combustion performance of a single-head DC combustion chamber are obtained.The cold flow field of the combustion chamber is within the range of the design point.With the increase of the inlet air volume,the speed in the combustion chamber continues to increase,but the main combustion zone can always maintain a symmetrical main recirculation zone structure to support the combustion reaction of the combustion chamber.As the oil-gas ratio increases,the temperature and pressure loss at the outlet of the combustion chamber increase.With the increase of the oil-gas ratio,the pollutant NOx emission increases first,then decreases,and then gradually increases.The combustion efficiency first increases and then decreases.As the inlet air temperature increases,the combustion chamber outlet temperature,pressure loss and NOx emissions all increase,while the combustion efficiency gradually decreases.With the increase of the inlet air flow rate,the pressure loss of the combustion chamber decreases,the temperature of the main combustion zone of the combustion chamber,the outlet temperature,and the combustion efficiency have a gradual increase trend,but this also brings about the continuous increase of NOx emissions.The main combustion zone flame structure,outlet average temperature,and outlet composition information,lean fuel flameout characteristics and other information during the combustion process of the single-head DC combustion chamber were gained through various measurement methods such as contact measurement and infrared spectroscopy.With the increase of the fuel-air ratio and the inlet air flow,the visible light flame photos taken by the digital camera show that the combustion flame burns violently,and the average outlet temperature and pollutant emissions also increase.The flame temperature map taken by the infrared thermal imaging camera shows that the high-temperature flame structure in the main combustion zone has a certain degree of stability,and the maximum temperature in the high-temperature zone increases slowly with the increase of the fuel-air ratio and the inlet air flow.In addition,the combustion characteristics of the direct current combustion chamber in this paper were carried out under the working condition of the inlet air flow rate of 0.1kg/s and the temperature of 300K.The lean oil ignition limit gas ratio of the combustion chamber was about 0.0188,and the flameout limit gas ratio was about 0.0084.Through comparison,it is found that the structure and distribution trend of the high temperature zone of the infrared image of the flame temperature are similar to the temperature distribution of the middle section of the combustion chamber in the numerical simulation to a certain extent.